This invention relates to a ring binder mechanism for retaining loose-leaf pages, and in particular to an improved mechanism for reducing a snapping motion of ring members as they close and for securely locking the closed ring members together. This invention further relates to an improved mechanism for easily opening and closing ring members that are filled with loose-leaf pages.
As is known in the art, a typical ring binder mechanism retains loose-leaf pages, such as hole-punched papers, in a file or notebook. It generally features multiple rings, each including two ring members capable of selectively opening to add or remove pages, or selectively closing to retain pages and allow them to move along the ring members. The ring members generally mount on two adjacent hinge plates that join together about a pivot axis and pivot within an elongated housing. The housing is slightly narrower than the joined hinge plates when the hinge plates are in a coplanar position (180°). So as the hinge plates pivot through this position, they deform the resilient housing and cause a tension spring force in the housing, urging the hinge plates to pivot away from the coplanar position (180°) either opening or closing the ring members. Thus, when the ring members are closed, this spring force resists hinge plate movement and clamps the ring members together. Similarly, when the ring members are open, the spring force holds them apart. An operator may typically overcome this force by manually pulling the ring members apart or pushing them together. In addition, in some mechanisms the operator may move a lever located at one or both ends of the mechanism for moving the hinge plates through the coplanar position (180°) to open or close the ring members (in addition to manually pulling the ring members apart or pushing them together).
One drawback to these typical ring binder mechanisms is that when the ring members close, the housing's spring force snaps them together rapidly and with a force that might cause fingers to be pinched between the ring members. The spring force also makes pivoting the hinge plates through the coplanar position (180°) difficult, making both opening and closing the ring members harder. Another drawback is that when the ring members are closed, they do not positively lock together. So if the mechanism accidentally drops, the ring members may unintentionally open. Still another drawback is that over time the housing may begin to permanently deform, reducing its ability to uniformly clamp the ring members together and possibly causing uneven movements or gaps between closed ring members.
To address these concerns, some ring binder mechanisms include a control slide directly attached to the lever. These control slides have inclined cam surfaces that project through openings in the hinge plates for rigidly controlling the hinge plates' pivoting motion both when opening and closing the ring members. Examples of these types of mechanisms are shown in U.S. Pat. No. 4,566,817 to Barrett, Jr., U.S. Pat. No 4,571,108 to Vogl, and U.S. Pat. No. 6,276,862 to Snyder, et al. and in U.K. Pat. No. 2,292,343 to Kokuyo Co. Ltd. Some of these cam surfaces include a stop for blocking the hinge plate's pivoting motion when the ring members are closed, locking the closed ring members together.
But these mechanisms still have drawbacks. When the ring members close, the housing's spring force may still snap them together. The spring force may also still make both opening and closing the ring members difficult. Furthermore, the control slides in these mechanisms, specifically the cam surfaces and stops, are complexly shaped and can be difficult and time consuming to fabricate. Moreover, since the control slides directly bias the hinge plates, they are usually relatively wide and may need to be constructed of large gauge metal to withstand forces associated with repeated use (i.e., repeatedly biasing the hinge plates to pivot). Therefore the openings in the hinge plates receiving these control slides may also be relatively wide, potentially weakening the hinge plates so that they too must also be made of large gauge metal. For these reasons, mass production of these mechanisms may be more costly.
Other types of ring binder mechanisms also attempt to address the issues of avoiding snapping motion of the ring members and positively locking the ring members together. For instance, some mechanisms arrange the hinge plates so that they never pass through the coplanar position (180°) in their pivoting motion. As a result of avoiding the coplanar position (180°) of the hinge plates, the ring members do not violently snap together upon closing. However, a closing force applied to the ring members is relatively weak so that it is necessary to provide a separate locking device to keep the ring members closed. Examples of this type of ring mechanism are shown in U.S. Pat. No. 5,660,490 to Warrington and G.B. Pat. No. 952,536 to Bennett. Other mechanisms arrange the hinge plates and housing so that the hinge plates are only weakly biased by the housing. A separate wire form spring is engaged with the underside of the hinge plates to provide a bias for pivoting the hinge plates to a position in which the ring members are open. An example of this ring binder mechanism construction is shown in U.S. Pat. Appl. Publ. No. 2003/0123923 to Koike, et al.
In the mechanisms described by Warrington and Koike, et al., the ends of the ring members are formed with hooks that are engaged upon closing to hold the ring members in the closed position. It requires some dexterity to manipulate the ring members to engage and disengage them. The manipulation becomes even more difficult if the ring members are filled with loose-leaf pages. Further, the hooks are more susceptible to forces that may unintentionally open the ring binder. Moreover, ring binder mechanisms having multiple ring members requiring simultaneous engagement or disengagement of hooks may make operation more awkward and difficult.
In the mechanism described by Bennett, the actuating lever is attached to the housing between the housing's ends. One end of the lever is bent slightly greater than a right angle so it is capable of directly pivoting the hinge plates to close the ring members and is further capable of blocking their pivoting motion, holding the ring members together. But this may not positively lock the ring members closed. The lever may slide out of the blocking position if the mechanism is accidentally dropped or if the housing deforms after repeated use.
Consequently, there is a need for a ring binder mechanism that securely and positively locks ring members together for retaining loose-leaf pages, but has ring members that easily open and close as pages accumulate and that do not snap together when the ring members close. The present invention is directed to such a ring binder mechanism.